1. Field of the Invention
The present invention relates to a nozzle of a solder suction device, and more particularly to a nozzle of a solder suction device particularly optical for solder removal job of electronic parts such as integrated circuits, capable of maintaining wettability with solder for a long time and many times of use, and excellent in corrosion resistance and heat transfer property.
2. Description of the Prior Art
A solder suction device is used for detaching a part soldered to a specific position or sucking the residual solder after detaching such parts, and it comprises a nozzle for sucking solder disposed at the front end portion, in addition to heating means such as heater and suction means such as vacuum pump.
Various structures have been proposed hitherto for this nozzle, including the one disclosed in the Japanese Utility Model Publication No. 48-59722. In this nozzle, a rear end part of an iron-made tube having a suction port at the tip is press-fitted into a stainless steel thin-wall pipe, and this thin-wall pipe is inserted into the copper-made iron tip main body so as to be formed firmly with this iron tip main body into one body. On the outer exposed portion of this iron tip main body, a chrome plating layer is applied and formed to apply heat resistant, rust preventive treatment, while a solder coating layer is applied and formed on the outer exposed portion of the tube to maintain wettability with the solder.
Thus, when using this solder suction device, the nozzle heated by the heating means is abutted against the solder to be removed. As a result, the solder is heated and melted by the nozzle heated to high temperature, and is sucked inside from the suction port of the nozzle by the suction means, and is reserved in a reserve tank with filter installed in the midst of suction route.
However, in such conventional nozzle structure, the following problems occurred, and their improvements have been demanded.
More specifically, in the nozzle in such structure, while repeating the solder removal jobs, when the suction means is operated by fitting the tip of the heated nozzle to the portion to be melted, that is, to the solder to be removed, the tip temperature of the nozzle may drop suddenly. As a result, the solder could not be melted sufficiently, and it could not be sucked in certain cases. To the contrary, considering such temperature drop to avoid such situation, if the initial heating temperature is kept at a higher level so as to melt the solder sufficiently even after drop, the heat above the permissible temperature is applied to the soldered parts, and the constituent parts of the heating means themselves may be damaged.
In particular, along with the rapid advancement in the electronics industry handling integrated circuits (or ICs) recently, the solder suction devices come to be used widely in solder removal jobs of such electronic components, and these problems have become very serious.
That is to say, strict permissible ranges are designated for heating temperature of these electronic components so as not to sacrifice their characteristics, and the use of solder suction device exceeding such permissible range is not allowed. Consequently, strict conditions are required for the heating temperature of the nozzle, and a very high precision is needed in its temperature control, but it was no longer possible to satisfy such strict conditions by the conventional nozzle structure stated above.
To solve the problems of the existing nozzle structure, the present inventors intensively tested and researched about the cause of the temperature drop, and discovered that the solder coating layer of the tube surface is melted by the heating temperature in the course of use for a long period or many times, and that the molten solder or flux corrodes the tip part of the iron main body, thereby forming a gap inside the chrome plated layer. This gap acts as an adiabatic layer between the iron tip main body and the tube, so that the heat transmission efficiency of the two is extremely lowered. As a consequence, the tip part heat of the tube is deprived of by the solder to be melted, and when the heating temperature is lowered, enough heat for raising the heating temperature to specified level is not supplemented, so that the temperature drop of the nozzle occurs.